I don't know why you guys recommend o-rings, the OP never mentioned anything regarding noise.
As for typing feel, I find o-ring reduce the travel distance and makes typing feel really weird. Not a fan of it personally. Unless the intent is for reducing key travel so you type "faster", in that case I'd say get a scissor switch and save yourself some money.
But from what I've gathered the OP just want different choices for typing other than MX Blue isn't it? ![huh :confused:](https://cdn.geekhack.org/Smileys/solosmileys/huh.gif)
Orings makes the landing very different. and reduced travel distance is a "technical" plus.. because it makes timing control easier when you're playing the typing games.
ALSO, i believe most people are doing O-rings "WRONG" and the 40a is still MUCH too hard.
I use the silicone rings I cut from silicone rubber dome keyboards. They're around 20-30a, they return that walkin' on sunshine feel of bottoming out a rubber dome, which takes away the harshness of Cherry MX landing.
![Cheesy :D](https://cdn.geekhack.org/Smileys/solosmileys/cheesy.gif)
a. Shore 20A = Rubber Band
b. Shore 40A = Pencil Eraser
c. Shore 60A = Car Tire Tread
d. Shore 70A* = Running Shoe Sole
e. Shore 80A = Leather Belt
f. Shore 100A = Shopping Cart Wheel